In this work we undertake a comparative study of mathematical models and related (CFD) simulations for the so-called RESS process (rapid expansion of supercritical solutions), which so much attention has attracted in the literature for the potential applications related to the production of microparticulates of selected materials with controllable morphology and narrow-size distributions using supercritical fluids. The numerical computation of supercritical fluid flows, in general, is extremely challenging because of the complexity of the physical processes involved and the different space and time scales. The aim of this study is the focused analysis of advanced mathematical modeling of the supercritical fluid expansion in the RESS process with the specific intent of delineating a possible strategy for optimizing operating parameters. Particularly, the research goals are to examine numerically, influences of temperature, pressure, composition, flow rate and reactor dimensions on the fluid hydrodynamic to undertake study of transport and growth of the recrystallized particles.